High loft nonwoven batting is a fibrous material which is commonly utilized in such products as filter media, bedspread, comforter, sleeping bag and seat cushion filling, and waterbed wave-dampening baffles. Such batting is conventionally formed from short length fibers (typically one to three inches in length) of either natural or manmade materials. High loft nonwoven batting is used in the above-mentioned applications because of its many unique physical characteristics, including high volume/low weight, softness and resilience, as well as fluid permeability.
Conventionally, such nonwoven batting is formed on specially designed textile machinery, and then stabilized in one of two ways. One method of stabilization is by the application of a binder or glue which fixes fibers in the desired position upon curing of the binder. This type of stabilization is commonly referred to as resin bonding. A second type of stabilization is referred to as thermal bonding, and requires the use of a blend of original fibers with secondary fibers or powders. These secondary fibers or powders will melt when heated and then solidify around the original fiber structure when cooled, so as to lock the fiber structure in position.
Resin bonding and thermal bonding impart a certain degree of tensile strength in the fiber batting which is sufficient to withstand regular handling and minor loads. However, applications of the batting which require higher tensile strengths also require that the conventional batting be reinforced in some fashion. Conventionally, such batting is reinforced with a woven or nonwoven fabric or netting which is attached to a high loft bonded batting.
One method for attaching the high strength fabric to the batting calls for a secondary step wherein the fabric is glued or laminated to the batting in a separate procedure from the batting production process. While the tensile strength of batting with a glued or laminated fabric is increased, this process requires a secondary production process including multiple material handling steps and extra manufacturing machinery and attendant labor, thereby increasing the manufacturing cost of the material. In addition, the fibers of the batting only adhere to the reinforcing fabric at discrete point locations where individual fibers touch the fabric. For this reason, the reinforcing fabric may be separated from the batting relatively easily because of the small attachment area. In order to improve the adhesion of the reinforcing fabric to the batting, one procedure calls for applying pressure to the layered composite during gluing. While this procedure improves adhesion and brings the fabric into contact with fibers deeper within the batting, the desired high loft characteristic is seriously reduced.
A second method for attaching a high strength fabric to a batting is referred to as "needle punching". In the needle punching process, an unbonded batting is laid on top of a high strength fabric. The combination is then punctured by a large number of reciprocating needles having multiple barbs. The needle barbs hook the unbonded fibers and force the fibers through the fabric so as to entangle the unbonded fibers around and through the reinforcing high strength fabric.
The needle punching process suffers several drawbacks. One problem is that the action of large numbers of needles forced through the batting results in a compression of the fibers, thereby increasing the density of the resulting fiber batting. This compression or increased density, is directly opposed to the desired open, high loft characteristics sought in the batting.
Another problem with the needle punching process lies in the fact that the large number of needles being forced through the batting frequently contact threads of the reinforcing fabric, breaking the fabric threads. This in turn reduces the tensile strength sought to be gained by the use of the fabric.